Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07H—SUGARS; DERIVATIVES THEREOF; NUCLEOSIDES; NUCLEOTIDES; NUCLEIC ACIDS
  • C07H19/00—Compounds containing a hetero ring sharing one ring hetero atom with a saccharide radical; Nucleosides; Mononucleotides; Anhydro-derivatives thereof
  • C07H19/01—Compounds containing a hetero ring sharing one ring hetero atom with a saccharide radical; Nucleosides; Mononucleotides; Anhydro-derivatives thereof sharing oxygen
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N43/00—Biocides, pest repellants or attractants, or plant growth regulators containing heterocyclic compounds
  • A01N43/90—Biocides, pest repellants or attractants, or plant growth regulators containing heterocyclic compounds having two or more relevant hetero rings, condensed among themselves or with a common carbocyclic ring system
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P33/00—Antiparasitic agents
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P33/00—Antiparasitic agents
  • A61P33/10—Anthelmintics

Definitions

• avermectin (previously referred to as C 076) is used to describe a series of compounds isolated from the fermentation broth of an avermectin producing strain of Streptomyces avermitilis and derivatives thereof. The morphological characteristics of the culture are completely described in U.S. Pat. No. 4,310,519.
• the avermectin compounds are a series of macrolides, each of which is substituted thereon at the 13 position with a 4'-( ⁇ -L-oleandrosyl)- ⁇ -L-oleandrose group.
• the avermectin compounds and the instant derivatives thereof have a very high degree of anthelmintic and anti-parasitic activity.
• avermectins such as 22,23-dihydro avermectin B1a/B1b also known as ivermectin disclosed in U.S. Pat. No. 4,199,569.
• the avermectin series of compounds which are isolated from a fermentation broth, have the following structure:
• R is the 4'-( ⁇ -L-oleandrosyl)- ⁇ -L-oleandrose group of the structure: ##STR1## wherein R is the 4'( ⁇ -L-oleandrosyl)- ⁇ -L oleandrose group of the structure: ##STR2## and wherein the broken line indicates a single or a double bond; R 1 is hydroxy and is present only when said broken line indicates a single bond;
• R 2 is iso-propyl or sec-butyl
• R 3 is methoxy or hydroxy.
• A1a, A1b, A2a, A2b, B1a, B1b, B2a and B2b are eight different major avermectin natural product compounds and they are given the designations A1a, A1b, A2a, A2b, B1a, B1b, B2a and B2b based upon the structure of the individual compounds.
• avermectin compounds are generally isolated as mixtures of a and b components. Such compounds differ only in the nature of the R 2 substituent and the minor structural differences have been found to have very little effect on the isolation procedures, chemical reactivity and biological activity of such compounds.
• the 13-deoxy avermectin aglycone compounds which lack the 13-disaccharide group are also starting materials for the instant compounds. They are disclosed in U.S. Pat. Nos. Re. 32,006 and 32,034.
• the avermectin B1 and 22.23 dihydro avermectin B1 compounds are of superior activity and mixtures of the a and b compounds have been selected to be marketed for their broad spectrum antiparasitic activity against both animal and plant parasites.
• the avermectin A2 and B2 compounds are of a considerably lower level of activity and are not marketed products.
• the conversion of the A2 and B2 compounds to the 23-deoxy- ⁇ 23,24-avermectin compounds produces compounds of significantly higher levels of activity.
• the A2 and B2 compounds which would normally be discarded in the preparation of the B1 and 22,23-dihydro B1 compounds, are utilized in the preparation of compounds with levels of activity commensurate with marketed products.
• the instant invention is concerned with certain derivatives of avermectin compounds wherein the 23 hydroxy group of avermectin A2 and B2 compounds is selectively eliminated to form 23-deoxy-23,24-bis-dehydro compounds of significant levels of anti-parasitic activity.
• avermectin elimination products A further object is to describe processes for the preparation of such compounds.
• a still further object is to describe the uses of such compounds as anti-parasitic and insecticidal agents. Still further objects will become apparent from a reading of the following description.
• the compounds of the instant invention have the following structural formula. ##STR3## wherein A represents a single bond or a double bond, R.sub. is iso-propyl or sec-butyl;
• R 2 is hydroxy, ketone, loweralkoxy, or protected hydroxy
• R 3 is hydrogen, halogen, or ketone, however R 3 is present only when A represents a single bond;
• R 4 is hydrogen, hydroxy, halogen, ##STR4##
• R 5 is hydroxy, ketone, -NR 6 R 7 or ##STR5## and
• R 6 and R 7 are independently hydrogen, loweralkyl or loweralkanoyl.
• loweralkyl is intended to include those alkyl groups containing from 1 to 6 carbon atoms in either a straight or branched chain or a cyclic configuration of from 3 to 6 carbon atoms.
• alkyl groups are methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, pentyl, hexyl, cyclopentyl, cyclohexyl and the like.
• loweralkanoyl is intended to include those alkanoyl groups of from 2 to 6 carbon atoms of either a straight or branched chain. Such groups are exemplified by acetyl, propionyl, butyryl, pentanoyl, hexanoyl and the like.
• halogen is intended to include the halogen atom, fluorine, chlorine, bromine and iodine.
• A is a single, or a double bond
• R 1 is isopropyl, or sec-butyl
• R 2 is hydroxy
• R 3 is hydrogen, halogen, hydroxy or oxo
• R 4 is hydrogen, hydroxy, halogen, 4'-R 5 -( ⁇ -L-oleandrosyloxy), 4"-R 5 -[4'-( ⁇ -L-oleandrosyl)- ⁇ -L-oleandrosyloxy
• R 5 is hydroxy, amino loweralkylamino, diloweralkylamino
• R 4 is halogen, and in particular, when R 4 is fluorine, and R 1 , R 2 , R 3 and R 5 are as defined above
• this representation of a mixture is sometimes done by referring, for example, to "the B1 or B2 compounds” or by separating the “a” compound from the “b” compound by a slash (/) such as B1a/B1b, B2a/B2b and the like.
• the compounds of the instant invention differ from other avermectin compounds in that the 23-hydroxy compounds, A2 and B2 compounds are converted into 23-dehydroxy- ⁇ 23,24 compounds. Such compounds are significantly superior to the A2 and B2 starting materials in their antiparasitic activity.
• the instant compounds are prepared from the suitably protected avermectin A2 or B2 compound, that is a compound with an unprotected 23-hydroxy group but with all other hydroxy groups protected.
• This compound is treated with the reagent diethylamino sulfurtrifluoride, generally referred to as DAST.
• DAST diethylamino sulfurtrifluoride
• This reagent is generally known in the art as a fluorinating reagent, however when used under the below described conditions and on the instant compounds, there is observed the surprising result that no fluoridation occurs anywhere on the avermectin molecule.
• the unprotected 23-hydroxy group is removed and a 23-24 double bond ( ⁇ 23,24) is formed.
• the reaction is carried out initially at a reduced temperature due to the reactivity of DAST. Generally temperatures of from -50° C. to -100° C. are utilized. It is preferred to carry out the reaction at about -78° C. since this is the temperature which is achieved by placing the reaction vessel in a dry-ice (solid carbon dioxide-acetone) bath. To further avoid side-reactions, the reaction is preferably carried out under a blanket of nitrogen an other inert atmosphere. The reaction is maintained at the reduced temperatures from 10 to 120 minutes and then is generally raised to room temperature slowly, over a period of from 60 to 180 minutes. To complete the reaction, the reaction vessel may be maintained at room temperature for from 1 to 8 hours or until analysis of aliguots of the reaction mixture indicate that the reaction is complete. Generally analytical procedures which can follow the disappearance of the 23-hydroxy group will give a good indication of the degree to which the reaction has progressed to completion. The product is isolated using standard techniques known to those skilled in the art and the protecting groups are removed following the procedures described below.
• the ultimate starting materials for the compounds of this invention are the avermectin fermentation products defined above which have the isopropyl or sec-butyl group at the 25 position.
• additional reactions are required to prepare many of the immediate starting materials for the instant compounds. Specifically, reactions are carried out at the 4', 4", 5', 10, 11 and 13, positions.
• various reactive groups to prevent the undesired reaction of such groups.
• protection of such reactive groups may facilitate the separation of the various products.
• the DAST reaction may be carried out without affecting the remainder of the molecule. Following the described reactions, the protecting groups may be removed and the unprotected product isolated.
• the protecting group employed is ideally one which may be readily synthesized, will not be affected by the reaction with the various reagents employed and may be readily removed without affecting any other functions of the molecule. It is noted that the instant protected compounds are novel and have considerable antiparasitic activity. They are included within the ambit of the instant invention.
• One preferred type of protecting group for the avermectin type of molecule is the tri-substituted silyl group, preferably the trialkyl silyl group.
• One especially preferred example, is the t butyl dimethylsilyl group.
• the reaction preparing the protected compound is carried out by reacting a hydroxy compound with the appropriately substituted silylhalide, preferably the silylchloride in an aprotic polar solvent such as dimethylformamide. Imidazole is added as a catalyst. The reaction is complete in from 1 to 24 hours at from 0° to 25° C. For the 5-position hydroxy group the reaction is complete in from 1/2 to 3 hours at from 0° C. to room temperature. This reaction is selective to the 5 position under the conditions above described and very little, if any, silylation is observed at other hydroxy substituted positions.
• the silyl groups are then removed after the other reactions have been carried out.
• the silyl group or groups are removed by stirring the silyl compound in methanol catalyzed by a catalytic amount of an acid, preferably a sulfonic acid such as p-toluene sulfonic acid.
• the reaction is complete in about 1 to 12 hours at from 0° to 50° C.
• the silyl group or groups can be removed with a hydrogen fluoride-pyridine complex in an organic solvent such as tetrahydrofuran.
• the reaction is complete in from about 3 to 24 hours and is preferably carried out at room temperature.
• reaction conditions which are generally applicable to the preparation of both the mono saccharide and aglycone involve dissolving the avermectin compound or the hydrogenated avermectin compound in an aqueous acidic non-nucleophilic organic solvent, miscible with water, preferably dioxane, tetrahydrofuran, dimethoxyethane, dimethyl formamide, bis-2-methoxyethyl ether, and the like, in which the water concentration is from 0.1 to 20% by volume.
• Concentrated sulfuric acid is added to the aqueous organic solvent to the extent of 0.01 to 10% (1 by volume.
• the reaction mixture is generally stirred at about 20-40° C., preferably at room temperature, for from 6 to 24 hours.
• the lower concentration of acid from about 0.01 to 0.1% will predominately produce the monosaccharide under the above reaction conditions.
• Higher acid concentrations, from about 1 to 10% will predominantly produce the aglycone under the above reaction conditions.
• Intermediate acid concentrations will generally produce mixtures of monosaccharide and aglycone.
• the products are isolated, and mixtures are separated by techniques such as column, thin layer preparative and high pressure liquid chromatography, and other known techniques.
• the acids which may be employed in the above process include mineral acids and organic acids such as sulfuric, hydrohalic, phosphoric, trifluoroacetic, trifluoro methane sulfonic and the like.
• the hydrohalic acids are preferably hydrochloric or hydrobromic.
• the preferred acid in the above process is sulfuric acid.
• a further procedure for the preparation of the monosaccharide or aglycone of the avermectin compounds or of the hydrogenated avermectin compounds utilizes a different solvent system for the mono saccharide and the aglycone.
• the procedure for the preparation of the monosaccharide uses 1% acid by volume in isopropanol at from 20°-40° C., preferably room temperature, for from 6 to 24 hours.
• 1% acid, by volume, in methanol under the foregoing reaction conditions has been found to be appropriate.
• the monosaccharide is prepared during the course of the reaction used to remove the trialkylsilyl protecting group. Since acid catalysis is used to remove the protecting group, this is expected. However, in such cases, both the desired product and the monosaccharide are prepared and they can be readily separated using the above-described techniques.
• the avermectin starting materials are oxidized at the 4' or 4"-position to the corresponding keto compound.
• the procedures for the preparation of such compounds are described in U.S. Pat. No. 4,427,663 to Mrozik. During the procedure the presence of any hydroxy groups at the 5 and 23-position will require that such hydroxy groups be protected in order that they too are not oxidized. The 7-hydroxy group is very unreactive and need not be protected. The procedure used to prepare the protected intermediates are described above.
• the oxidation reaction is carried out in an inert solvent such as methylene chloride using oxalyl chloride or trifluoroacetic anhydride with dimethylsulfoxide as the oxidizing agent.
• the reaction proceeds by dissolving the oxalyl chloride or trifluoroacetic anhydride and dimethylsulfoxide (or other oxidizing reagents) in methylene chloride cooled to from -50° to -80° C. and adding dropwise a methylene chloride solution of the avermectin compound to be oxidized.
• the addition is carried out over a period of from 15 minutes to 1 hour and then triethylamine is added dropwise over a period of from 1 to 15 minutes.
• the reaction mixture is then allowed to warm to room temperature over a period of from 1/2 to 1 hour.
• the 4' or 4"-keto compound is isolated using techniques known to those skilled in the art.
• the reaction is carried out in an inert solvent such as methanol at from -10° to +25° C. using ammonium salts and sodium cyanoboro hydride as the aminating and reducing reagents, respectively.
• the reaction is complete in from 15 minutes to 24 hours and the product 4"-deoxy-4"-amino compound is isolated using techniques known to those skilled in the art. Suitable ammonium salts are the acetate, propionate, benzoate and the like. The acetate is preferred.
• methyl ammonium salts can be used in place of the ammonium salts to prepare the monomethyl substituted compound directly.
• the same reagents, salts and reaction conditions as described above can be used for such a reaction.
• substitution reaction wherein the substituent is an acyl function is carried out using an acylating reagent in the presence of a base in an inert solvent.
• the acylation of avermectin compounds is fully described in U.S. Pat. No. 4,201,861 to Mrozik et al.
• the preferred acylating reagents are loweralkanoyl anhydrides, loweralkanoyl halides, substituted benzene sulfonyl chlorides, lower alkyl sulfonyl chlorides, and the like.
• the reaction is carried out in an inert solvent such as methylene chloride in the presence of a non reactive base such as pyridine or triethylamine in order to neutralize the acid produced during the course of the reaction.
• a non reactive base such as pyridine or triethylamine
• the reaction temperature is from -10° to 25° C. and the reaction is complete in from 5 minutes to 8 hours.
• the product is isolated using known techniques.
• the reaction for the preparation of the 4'- or 4"-deoxy-4'- or 4"-dialkylamino compounds is carried out using the alkylating reaction conditions of an excess of a carbonyl compound, preferably formaldehyde and a reducing agent such as sodium cyano borohydride, in methanol.
• a carbonyl compound preferably formaldehyde and a reducing agent such as sodium cyano borohydride
• the reaction is carried out in a solvent suitable to dissolve the organic starting material using excess aqueous formaldehyde along with the presence of a small amount of acid such as acetic acid to facilitate the reaction.
• the reaction is carried out at from -10° to +25° C. with the solution of the avermectin compound in methanol added dropwise over a period of from 30 to 60 minutes to the alkylating reagent mixture and the product is isolated using known techniques.
• the hydroxy group at 5 may be alkylated following the procedures described in U.S. Pat. No. 4,200,581 to Fisher et al.
• novel compounds of this invention have significant parasiticidal activity as anthelmintics, ectoparasiticides, insecticides and acaricides, in human and animal health and in agriculture.
• helminthiasis The disease or group of diseases described generally as helminthiasis is due to infection of an animal host with parasitic worms known as helminths. Helminthiasis is a prevalent and serious economic problem in domesticated animals such as swine, sheep, horses, cattle, goats, dogs, cats and poultry. Among the helminths, the group of worms described as nematodes causes widespread and often times serious infection in various species of animals.
• the most common genera of nematodes infecting the animals referred to above are Haemonchus, Trichostrongylus, Ostertagia, Nematodirus, Cooperia, Ascaris, Bunostomum, Oesophagostomum, Chabertia, Trichuris, Strongylus, Trichonema, Dictyocaulus, Capillaria, Heterakis, Toxocara, Ascaridia, Oxyuris, Ancylostoma, Uncinaria, Toxascaris and Parascaris.
• the parasitic infections known as helminthiases lead to anemia, malnutrition, weakness, weight loss, severe damage to the walls of the intestinal tract and other tissues and organs and, if left untreated, may result in death of the infected host.
• the substituted avermectin compounds of this invention have unexpectedly high activity against these parasites, and in addition are also active against Dirofilaria in dogs, Namatospiroides, Svphacia, Aspiculuris in rodents, arthropod ectoparasites of animals and birds such as ticks, mites, lice, fleas, blowfly, in sheep Lucilia sp., biting insects and such migrating diperous larvae as Hypoderma sp. cattle, Gastrophilus in horses, and Cuterebra sp. in rodents.
• the instant compounds are also useful against parasites which infect humans.
• the most common genera of parasites of the gastro intestinal tract of man are Ancylostoma, Necator, Ascaris, Strongyloides, Trichinella, Capillaria, Trichuris, and Enterobius.
• Other medically important genera of parasites which are found in the blood or other tissues and organs outside the gastrointestinal tract are the filiarial worms such as Wuchereria, Brugia, Onchocerca and Loa, Dracunculus and extra intestinal stages of the intestinal worms Strongyloides and Trichinella.
• the compounds are also of value against arthropods parasitizing man, biting insects and other dipterous pests causing annoyance to man.
• the compounds are also active against household pests such as the cockroach, Blatella sp., clothes moth, Tineola sp., carpet beetle, Attagenus sp., and the housefly Musca domestica.
• the compounds are also useful against insect pests of stored rains such as Tribolium sp., Tenebrio sp. and of agricultural plants such as two spotted spider mites, (Tetranychus sp.), aphids, (Acyrthiosiphon sp.); against migratory orthopterans such as locusts and immature stages of insects living on plant tissue.
• the compounds are useful as a nematocide for the control of soil nematodes and plant parasites such as Meloidogyne spp. which may be of importance in agriculture.
• the compounds are active against other plant pests such as the southern army worm and Mexican bean beetle larvae.
• a unit dosage form such as a capsule, bolus or tablet, or as a liquid drench where used as an anthelmintic in mammals.
• the drench is normally a solution, suspension or dispersion of the active ingredient usually in water together with a suspending agent such as bentonite and a wetting agent or like excipient.
• a suspending agent such as bentonite and a wetting agent or like excipient.
• the drenches also contain an antifoaming agent.
• Drench formulations generally contains from about 0.001 to 0.5% by weight of the active compound.
• Preferred drench formula tions may contain from 0.01 to 0.1% by weight.
• the capsules and boluses comprise the active ingredient admixed with a carrier vehicle such as starch, talc, magnesium stearate, or di calcium phosphate.
• avermectin derivatives in a dry, solid unit dosage form, capsules, boluses or tablets containing the desired amount of active compound usually are employed.
• These dosage forms are prepared by intimately and uniformly mixing the active ingredient with suitable finely divided diluents, fillers, disintegrating agents and/or binders such as starch, lactose, talc, magnesium stearate, vegetable gums and the like.
• suitable finely divided diluents, fillers, disintegrating agents and/or binders such as starch, lactose, talc, magnesium stearate, vegetable gums and the like.
• Such unit dosage formulations may be varied widely with respect to their total weight and content of the antiparasitic agent depending upon factors such as the type of host animal to be treated, the severity and type of infection and the weight of the host.
• the active compound When the active compound is to be administered via an animal feedstuff, it is intimately dispersed in the feed or used as a top dressing or in the form of pellets which may then be added to the finished feed or optionally fed separately.
• the antiparasitic compounds of our invention may be administered to animals parenterally, for example, by intraruminal, intramuscular, intratracheal, or subcutaneous injection in which event the active ingredient is dissolved or dispersed in a liquid carrier vehicle.
• the active material is suitably admixed with an acceptable vehicle, preferably of the vegetable oil variety such as peanut oil, cotton seed oil and the like.
• parenteral vehicles such as organic preparation using solketal, glycerol formal, and aqueous parenteral formulations are also used.
• the active avermectin compound or compounds are dissolved or suspended in the parenteral formulation for administration; such formulations generally contain from 0.005 to 5% by weight of the active compound.
• antiparasitic agents of this invention find their primary use in the treatment and/or prevention of helminthiasis, they are also useful in the prevention and treatment of diseases caused by other parasites, for example, arthropod parasites such as ticks, lice, fleas, mites and other biting insects in domesticated animals and poultry. They are also effective in treatment of parasitic diseases that occur in other animals including humans.
• arthropod parasites such as ticks, lice, fleas, mites and other biting insects in domesticated animals and poultry. They are also effective in treatment of parasitic diseases that occur in other animals including humans.
• the optimum amount to be employed for best results will, of course, depend upon the particular compound employed, the species of animal to be treated and the type and severity of parasitic infection or infestation.
• compositions are provided in which the active compound or compounds are intimately dispersed in an inert carrier or diluent.
• inert carrier is meant one that will not react with the antiparasitic agent and one that may be administered safely to animals.
• a carrier for feed administration is one that is, or may be, an ingredient of the animal ration.
• compositions include feed premixes or supplements in which the active ingredient is present in relatively large amounts and which are suitable for direct feeding to the animal or for addition to the feed either directly or after an intermediate dilution or blending step.
• Typical carriers or diluents suitable for such compositions include, for example, distillers' dried grains, corn meal, citrus meal, fermentation residues, ground oyster shells, wheat shorts, molasses solubles, corn cob meal, edible bean mill feed, soya grits, crushed limestone and the like.
• the active compounds are intimately dispersed throughout the carrier by methods such as rinding, stirring, milling or tumbling.
• Compositions containing from about 0.005 to 2.0% by weight of the active compound are particularly suitable as feed premixes.
• Feed supplements, which are fed directly to the animal contain from about 0.0002 to 0.3% by weight of the active compounds.
• Such supplements are added to the animal feed in an amount to give the finished feed the concentration of active compound desired for the treatment and control of parasitic diseases.
• the desired concentration of active compound will vary depending upon the factors previously mentioned as well as upon the particular avermectin derivative employed, the compounds of this invention are usually fed at concentrations of between 0.00001 to 0.002% in the feed in order to achieve the desired antiparasitic result.
• the avermectin compounds of this invention are also useful in combatting agricultural pests that inflict damage upon crops while they are growing or while in storage.
• the compounds are applied using known techniques as sprays, dusts, emulsions and the like, to the growing or stored crops to effect protection from such agricultural pests.
• the individual substituted avermectin components may be prepared and used in that form.
• mixtures of two or more of the individual avermectin components may be used, as well as mixtures of the parent avermectin compounds, other avermectin compounds or other active compounds not related to avermectin, with the compounds of this invention.
• the starting materials for the compounds of this invention are very often prepared in a ratio of about 80% avermectin B1a or A1a and 20% avermectin B1b or A1b.
• the preferred composition of this invention is one which contains about 80% of the "a" component and 20% of the "b" component.
• the substituted avermectin derivatives prepared in the following examples are generally isolated as amorphous solids and not as crystalline solids. They are thus characterized analytically using techniques such as mass spectrometry, nuclear magnetic resonance, and the like. Being amorphous, the compounds are not characterized by sharp melting points, however, the chromatographic and analytical methods employed demonstrate the purity of the compounds.
• the various starting materials therefor are avermectin co;npounds or derivatives of avermectin compounds.
• the aver mectin compounds and the preparation and isolation thereof from fermentation broths are described in U.S. Pat. No. 4,310,519 issued Jan. 12, 1982.
• the 22,23-dihydro derivatives of avermectin compounds are described in U.S. Pat. No. 4,199,569.
• the aglycone and monosaccharide derivatives of avermectin compounds are described in U.S. Pat. No. 4,206,205.
• the 13-deoxy compounds are described in U.S. Pat. Nos. Re 32,006 and 32,034.
• the 4 and 4" amino compounds are described in U.S. Pat. No. 4,427,663.
• the acyl derivatives are disclosed in U S. Pat. No. 4,201,861
• the epoxide derivatives are disclosed in U.S. Pat. No. 4,530,971.
• the 13 keto and amino compounds are disclosed in U.S. Pat. No. 4,579,864, and the o-alkyl compounds are disclosed in U.S. Pat. No. 4,200,581.
• the 13 (alkoxy)methoxy compounds are disclosed in U.S. Pat. No. 4,587,247.
• the following examples are being provided in order that the invention may be more fully understood. They are not to be construed as being limitative of the invention.
• anhydrous hydrogen fluoride pyridine tetrahydrofuran mixture prepared by mixing 14.0 ml of THF, 4.0 ml of pyridine and 2.0 ml of commercial HF pyridine (consisting of 70 % HF and 30 % of pyridine, supplied by Aldrich Chemical Company) was kept at room temperature for two days.
• reaction mixture was poured into dilute aqueous sodium bicarbonate solution and extracted with EtOAc to give 27 mg of 23 24-dehydroavermectin B2a and/or B2b as a glass, which was fully characterized by its UV spectrum, EI and FAB mass spectra, and 1 H-, and 13 C-NMR spectra including 1 H-"COSY" and 13 C-APT.
• the product is purified by preparative silica gel layer chromatography with a CH 2 Cl 2 -MeOH 93:7 solvent mixture, and is identified by NMR and mass spectra as 4"-deoxy-4"-methylamino-5-O-t-butyldimethylsilyl-23,24-dehydroavermectin B2a/B2b

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  • 1989-01-13 US US07/296,172 patent/US4895837A/en not_active Expired - Fee Related
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